The quality of electronic imaging, like any other form of photography, is a function of lighting conditions. Many conventional film cameras use photodiodes in single or matrix configurations to adjust exposure. The possibility also exists for doing illuminant color detection or type detection as described in U.S. Pat. No. 4,827,119. The illuminant detection described in that patent requires a real time signal input. Electronic still cameras already have a sensor for detecting light and for providing a real time signal. It therefore would be advantageous to use this same sensor. The state of solid state image sensors has advanced to the point that overflow protection is provided for preventing a phenomena called "blooming" from occurring. This phenomena is defined as the spreading of the charge accumulated in a light sensing element in such a way as to interact with the charges accumulated in adjacent light sensing elements. Various techniques are used to eliminate or control "blooming". Some examples are provided in the following patents:
U.S. Pat. No. 3,896,485, entitled "Charge-Coupled Device with Overflow Protection" by Early.
U.S. Pat. No. 3,896,474, entitled "Charge Coupled Area Imaging Device with Column Anti-Blooming Control" by Amelio et al.
U.S. Pat. No. 4,242,599, entitled "Charge Transfer Image Sensor with Antiblooming and Exposure Control" by Suzuki.
U.S. Pat. No. 4,373,167, entitled "Solid State Image Sensor with Overflow Protection and High Resolution" by Yamada.